The embodiments described herein relate generally to detecting radiation, and more particularly, to a water-based radiation detector.
At least some known passenger screening systems detect contraband. As used herein, the term “contraband” refers to illegal substances, explosives, narcotics, weapons, a threat object, and/or any other material that a person is not allowed to possess in a restricted area, such as an airport. Contraband detection may involve a combination of sensors and structures to control a flow of passengers and/or cargo. Contraband may also include objects that can be carried in exempt or licensed quantities intended to be used outside of safe operational practices, such as the construction of dispersive radiation devices.
One apparatus for detecting contraband is a radiation detector. Radiation detectors may detect alpha, beta, positron, fast electron, neutron and/or gamma ray radiation to identify one or more radionuclides in a radiation source. At least some known radiation detectors include ionizing gas chambers, direct-absorption semiconductors, and indirect detectors that use a scintillating material connected to a semiconductor or photomultiplier tube (PMT). However, these known detectors have certain disadvantages. For instance, ionizing gas chambers exhibit low absorption of radiation due to the low density of the gas medium therein through which radiation products travel. Moreover, PMTs used in indirect radiation detectors are expensive, as are direct-absorption semiconductor detectors.